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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 6541-6548 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Time-dependent density-functional theory (TDDFT) calculations were carried out to predict the Q-like bands of the two structural isomers of the phenylene-linked free-base (FBBC) and zinc (ZnBC) bacteriochlorin dimers. The calculated singlet excitation energies and oscillator strengths for the low-lying excited states of the reference monomers, FBBC and ZnBC, are quite consistent with recent ab initio calculations. The 1,3 and 1,4-phenylene-linked dimers have monomer-like Q bands and new Q′ bands comprised of the cross-linked (i.e., charge transfer) excitations from the FBBC (ZnBC) ring to the ZnBC (FBBC) ring, whose excitation energies are slightly and considerably red-shifted by about 0.03 eV and 0.5–0.7 eV compared to the monomers, respectively. The monomer-like Qx bands are of the mixed highest occupied molecular orbital (HOMO)→lowest unoccupied molecular orbital (LUMO) excitations in the Qx bands from the different bacteriochlorin rings, whose origin is the coupling of the Qx transition dipole moments through the π–π interaction between the unreduced pyrroles situated across the phenylene group. This mixing character is still maintained in the monomers separated by the same distance in the dimer, which is quite different from previous TDDFT calculations for the phenylene-linked free-base and zinc porphyrin dimers. The present dimers may show a more efficient Qx excitation energy transfer between the bacteriochlorins via each's through-space overlapped LUMOs than the conventional porphyrin dimers. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-1463
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die autonomische Irritation der Verdauungsorgane und des Harnweges hat auf die Herzfunktion einen Einfluß. Durch die elektrophysiologische Technik wurde dieser Mechanismus aufgeklärt. 1. Es wurde an zwei Patienten mit Arrhythmie, von denen der eine an Dysurie und der andere an Cholelithiasis leidet, gezeigt, daß diese Arrhythmie, die durch die Überdehnung der Harnblase und durch die Operation ausgelöst war, sofort nach dem Urinieren und der Cholecystektomie wieder verschwand. 2. Bei der experimentellen Überdehnung der Harnblase des Hundes, des Kaninchens und des Meerschweinchens trat vorübergehender Abfal des Blutdruckes, Koronarinsuffizienz im EKG und/oder Arrhythmie auf. Diese Veränderungen verschwanden nach dem Urinieren. 3. Es wurde am Meerschweinchen gezeigt, daß die durch die Überdehnung der Harnblase verursachten EKG-Veränderungen durch eine Rückenmarksdurchschneidung im lumbosakralen Segment plötzlich verschwanden. 4. Elektrophysiologische Untersuchungen zeigten, daß die neurale Transmission von der Harnblasenwand zum herz im Zusammenhang mit dem Vago-vagal-Reflex steht. 5. Es ist bisher bekannt, daß die Irritation der Gallenblase und des Verdauungsorganes bisweilen Myokardveränderungen verursacht. Dieser Mechanismus ließ sich dadurch beweisen, daß die Arrhythmie oder die EKG-Veränderungen zur gleichen Zeit wie die gesteigerte elektrische Reaktion des Vago-vagal-Reflexes, nach Irritation der Gallenblase oder Pylorusregion auftraten.
    Abstract: Résumé 1. Chez deux patients atteints de rétention urinaire de causes différentes, on a observé pendant la dilatation de la vessie une arythmie, qui disparaît promptement lorsque l'on vide la vessie par sondage. 2. La dilatation expérimentale de la vessie chez l'animal produit une chute transitoire de la pression artérielle, des signes d'insuffisance coronaire dans l'ECG avec arythmie, ou de l'arythmie seule. Ces troubles disparaissent lorsque la vessie est vidée. 3. Chez le cobaye, on a montré que les altérations de l'ECG produites par dilatation de la vessie disparaissent après section de la moelle entre les segments lombaire et sacré. 4. Chez le lapin, on a constaté que l'irritation de la vésicule biliaire ou du pylore influence l'ECG par réflexe vago-vagal. 5. L'emploi, d'une technique électrophysiologique a permis de montrer que la transmission nerveuse des parois de la vessie, de la vésicule biliaire ou du pylore au coeur se fait par réflexe vago-vagal.
    Notes: Summary The autonomic irritation from the digestive organs and the urinary tract influences upon the cardiac function. Using the electrophysiological technique, this mechanism was revealed. 1. The authors presented two patients with arrhythmia, the one suffering from dysuria and the other suffering from cholelithiasis. These arrhythmias appeared with overdistension of the urinary bladder and operative procedure, and disappeared promptly by urination and cholecystectomy. 2. Experimental overdistension of the urinary bladder in dogs, rabbits and guinea pigs resulted in transitory fall of blood pressure, pictures of coronary insufficiency in EKG and/or appearance of arrhythmias. These changes disappeared by relieving the bladder of overdistension. 3. In guinea pigs it was shown that the EKG changes produced by overdistension of the urinary bladder were erased by transection of the spinal cord between the lumbo-sacral segment. 4. Electrophysiological study showed that the nervous transmission from the bladder wall to the heart was related to, vago-vagal reflex. 5. It was known that the irritation of the gallbladder and gastro-enterical tract sometimes produced the myocardial changes. This mechanism was revealed by the result that arrhythmia or EKG changes appeared at the same time when electrical response of vago-vagal reflex was increased after irritation of the gall-bladder or the pyloric region.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1463
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Der Vago-vagal-Reflex spielt eine wichtige Rolle in der Genese des „Irritations-syndroms”. Die elektrophysiologische Beschaffenheit des Vago-vagal-Reflexes wurde in Verbindung mit dem Mechanismus des „Irritationssyndroms” studiert. 1. Der Vago-vagal-Reflex, welcher mit Strychnin verstärkt wurde, bewirkte eine deutliche Veränderung im EKG, ähnlich einem Zustand bei Irritation. 2. Das für den Vago-vagal-Reflex verantwortliche Gebiet sind nicht nur die Vaguskerne, sondern auch andere Strukturen des Mittelhirns sowie die Formatio reticularis. 3. Eine mäßige Hypothermie beim Tier erzeugt eine deutliche Verstärkung der Vago-vagal-Reflex-Antwort. Die Autoren haben versucht, die unangenehme Komplikation bei Hypothermiebehandlung, so z. B. die Verdauungskanalblutung, zu erklären. 4. Der „Irritationssyndrom”-Mechanismus wurde in Verbindung mit diesen Beobachtungen diskutiert.
    Abstract: Résumé Le réflexe vago-vagal joue un rôle important pour la genèse du «phénomène de Reilly». Quelques caractères électrophysiologiques du réflexe vago-vagal furent étudiés pour mettre le mécanisme du «phénomène de Reilly» en évidence. 1. Le réflexe vago-vagal augmenté par la strychnine provoqua une perturbation de l'électrocardiogramme, semblable à l'état d'irritation. 2. La région responsable du réflexe vago-vagal ne comprend pas seulement les noyaux du nerf vague, mais aussi d'autres structures comme la formation réticulée. 3. L'hypothermie modérée provoque une augmentation du réflexe vago-vagal. On essaie d'expliquer le mécanisme des complications fâcheuses, telles que l'hémorragie du canal digestif en cas de thérapie par l'hypothermie. 4. Le mécanisme du «phénomène de Reilly» est discuté en rapport avec ces observations.
    Notes: Summary The vago-vagal reflex plays an important role in the occurrence of “Irritation syndrome”. Electrophysiological properties of the vago-vagal reflex were studied in connection with the mechanism of “Irritation syndrome”. 1. The vago-vagal reflex augmented by strychnine provoqued a remarkable disturbance in EKG as in the state of irritation. 2. The region responsible for vago-vagal reflex involved not only the vagal nuclei but also other structures in the midbrain such as the reticular formation. 3. Moderate hypothermia evoqued a marked augmentation of the vago-vagal reflex response. Attempt was made to explain the troublesome complications of hypothermia-therapy such as hemorrhage of digestive canal. 4. The mechanism of “Irritation syndrome” was discussed in connection with these observations.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Molecular engineering 2 (1993), S. 339-347 
    ISSN: 1572-8951
    Keywords: Silicon-containing polymers ; electric conduction ; electronic structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The electronic structures, in the optimized geometries, of polysilacyclopentadiene (polysilole), polygermacyclopentadiene, and silole-thiophene alternating copolymer, have been studied theoretically using the one-dimensional tight-binding self-consistent field crystal orbital (SCF-CO) method. It has been found that the band gap values of these polymers are slightly smaller than those of the ordinary five-membered polyheterocycles such as polythiophene. The larger σ-polarized nature between the Group IV atom and the carbon atom might be expected to exhibit a different behaviour, compared with polythiophene, when they are doped with ann-type dopant.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-8951
    Keywords: Electron donor-acceptor moieties ; crystal orbitals ; polythiophene ; polyfuran ; polypyrrole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Theoretical results on the geometric and electronic structures of some donor-acceptor polymers based on polythiophene (X=S), polyfuran (X=O) and polypyrrole (X=NH) were obtained, using a one-dimensional tight-binding self-consistent field crystal-orbital (SCF-CO) method at the MNDO-AM1 level of approximation. The repeat unit of these polymers consits of a bithiophene, furan or bipyrrole unit bridged by an electron-accepting group or . The optimized geometries of the polymers show a strong dependence on the nature of the electron donating group X. All the polymers studied are predicted to have band gap values ranging between 1 eV and 2 eV. An analysis of their π-bond order data and of the patterns of their frontier orbitals shows they have benzenoid-like electronic structures.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Molecular engineering 3 (1994), S. 301-309 
    ISSN: 1572-8951
    Keywords: Silicon-containing polymers ; electronic structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The electronic structures of one-dimensional and two-dimensional siloxene (Si6O3H6) model compounds have been examined theoretically, using the semiempirical tight-binding self-consistent field crystal orbital (SCF-CO) method. These compounds are formed by silicon-based chain and planar structures containing a regular array of oxygen atoms. Results show that the two-dimensional polysilane in which OH groups are substituted for H atoms possesses a relatively smaller direct gap than other siloxenes. It is assumed that the electronic structures of siloxenes are affected not only by the dimensionality of Si-Si σ-conjugational networks due to an array of oxygen atoms, but also by the diminishing of the electron population in the Si-Si bonding orbitals caused by oxygen atoms with large electronegativity.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Molecular engineering 3 (1994), S. 311-320 
    ISSN: 1572-8951
    Keywords: Si-containing polymers ; electronic structure ; thermochromism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The electronic structures and conformations in the optimized geometries of polysilole and its derivatives are studied theoretically, using the one-dimensional tight-binding self-consistent field crystal orbital (SCF-CO) method. It has been found that the copolymer formed by alternating aromatic silole and quinoid thiophene has a relatively small bandgap value. We observe that polysilole may show an interesting thermochromic behavior, because the conformation of polysilole is considerably easier to change at lower temperature than that of polythiophene.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Molecular engineering 6 (1996), S. 363-371 
    ISSN: 1572-8951
    Keywords: Silicon-based material ; electronic structure ; excited state
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The singlet excited states in the optimized geometries of bicyclo[2.2.0]hexasilane and tricyclo[4.2.0.02,5]octasilane are studied theoretically using the ab initio molecular orbital method at the RHF/3-21G* level with the all-singles CI approximation. These molecules are found to have zigzag structures in both the ground states and the singlet excited states corresponding to the lowest absorptions, and the estimated Stokes shifts between the lowest absorption and fluorescence are similar to the experimental values.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 2753-2758 
    ISSN: 0887-624X
    Keywords: iodine ; polysilane ; visible absorption ; dialkylaminophenyl substituent ; charge transfer ; σ-conjugation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The doping effects on optical and electrical properties of polysilanes were investigated by in-situ measurement. When polysilanes bearing a p-N,N-dialkylaminophenyl substituent were doped with iodine vapor, drastic spectral changes were observed. The evolved visible absorption up to 700 nm was found to be strong and stable compared to that of iodine-doped polysilanes such as poly(methylphenylsilane). On the basis of the studies concerning iodine doping of the related p-N,N-dimethylaminophenyl-substituted silane and disilane, and also theoretical calculations, this new absorption can be best interpreted by the result of charge transfer consisting of the strong interaction between iodine and dialkylamino substituents in the polysilanes. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 393-401 
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The geometric and electronic structures of n-tetrasilane cation and anion radicals as models of doped linear polysilanes are studied theoretically using an ab initio molecular orbital method at the UMP2/6-31 + G(d, p) level of calculations. It is found that the trans-conformations in these molecules are the most stable structures in each ground state and that the energy differences between the cis- and trans-conformations are 3 kcal/mol for the cation radical and 11 kcal/mol for the anion radical. There exists no stable gauche-conformation in these molecules in contrast to neutral n-tetrasilane. It seems that the weakening of the central silicon-silicon bond on doping is connected to the concentration of the charge distributions on central silicon atoms with the change from trans- to cis-conformations in both n-tetrasilane cation and anion radicals. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 62: 393-401, 1997
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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